K4169合金在模拟烟气环境中的热腐蚀行为

Hot-corrosion behavior of alloy K4169 in simulated flue-gas

采用XRD、SEM、EDS以及EPMA等分析方法,研究铸态K4169合金及固溶-时效处理后K4169合金在650℃下模拟烟气(75%Na_2SO_4+25%NaCl)环境中的热腐蚀行为.结果表明:2种状态的K4169合金腐蚀动力学曲线均遵从抛物线规律;2种试样的腐蚀产物均分为2层,其内腐蚀层的腐蚀产物为Ni_3S_2;铸态合金的外腐蚀层产物分3部分:最外侧为Ni_3S_2薄层;中间以Fe_3O_4,NiO,NiFe_2O_4等氧化产物为主;内侧以Cr-O为主,有少量的铌、铝、钛的氧化物;固溶-时效态合金外腐蚀层的腐蚀产物为外侧以Fe_3O_4、NiO、NiFe_2O_4为主和内侧以Cr-O为主的2部分构成.2种状态合金的热腐蚀规律均遵循碱性机制.固溶-时效态试样的腐蚀层厚度低于铸态试样,固溶-时效处理能显著提高K4169合金的抗热腐蚀能力.

Hot-corrosion behavior of as-cast K4169 alloy and K4169 alloy processed with solid-solution and ageing treatment were investigated in environment of simulated flue-gas（75%Na2 SO4＋25 %NaCl） at 650 ℃ by using analysis means of XRD, SEM, EDS and EPMA. The investigation result showed that the corrosion kinetic curves of K4169 alloys in both states would follow a parabolic law, and the corrosion film structures of two kinds of K4169 alloys are divided into two layers. Their corrosion products would consist of two layers： the inside layer was Ni3S2 and the outer layer corrosion products of as-cast K4169 were com： posed of three part. The most outer part was Ni3Szthin layer, middle part was mainly Fe304, NiO, NiFe2O4 oxidation products, and inside part was Cr-O and a small amount of niobium, aluminum, titanium ox- ide. The outer layer of corrosion products of K4169 alloy processed with solid-solution and ageing treat- ment was composed mainly of Fe3O4, NiO, and NiFe2O4 and the inner layer was mainly Cr--O. Corro- sion behaviors of both K4169 alloys would follow alkaline corrosion mechanism. Corrosion layer thickness of K4169 alloy processed with solid-solution and ageing treatment was less than that of the as-cast sample. The solid-solution and ageing treatment would significantly improve the hot-corrosion resistance of the K4169 alloy.